Jewish groups and Italian politicians have expressed anger at the decision to grant day release to a convicted Nazi criminal under house arrest in Rome.

Erich Priebke, 93, is serving a life sentence for the murder of 335 people at the Ardeatine Caves outside Rome.

The 1944 massacre was a reprisal ordered by Adolf Hitler after partisans killed a patrol of 33 German soldiers.

The judge's decision also outraged the capital's mayor who said the city would never forget the massacre.

"At this time the city of Rome's solidarity goes out to all the victims of the Nazi-Fascist barbarity," Walter Veltroni said.

Priebke was one of several officers present during the killing of over 300 men and boys, 75 of whom were Jewish, at the caves south of Rome.

He spent most of his life in Argentina before being extradited to Italy in 1994, where he was allowed to serve his life sentence under house arrest due to his age and health problems.

'No mercy'

He will now be allowed to leave his flat, lent to him by a lawyer who campaigned for his freedom, during the day.

The decision allows him to go to his lawyer's office "every day, freely" and also to "go out to satisfy, at nearby places and for the time strictly necessary, the indispensable necessities of life".

His lawyer, Paolo Giachini, said that since his arrest Priebke had been writing a book and would probably use the time to consult documents and continue research.

The head of the Union of Italian Jewish Communities said the move was another concession to a man who did not deserve it.

"This is clearly another act of leniency towards a man who showed no mercy in killing 335 innocent civilians and has shown no remorse since," Renzo Gattegna told the German news agency Deutsche Presse-Agentur.